1. Field of the Invention
The described invention relates to the field of integrated circuit packages. In particular, the invention relates to an apparatus and method of cooling an integrated circuit package.
2. Description of Related Art
An integrated circuit package houses an integrated circuit die. The integrated circuit die may generate a substantial amount of heat and may require substantial cooling to prevent the integrated circuit from overheating. In some cases, large heat sinks with fans are attached to the outside of the integrated circuit package.
FIG. 1 is a schematic diagram that shows a prior art integrated circuit package 5. An integrated circuit die 10 is typically made from a semiconductor material such as silicon. The electrical components are formed on one side of the integrated circuit die, herein referred to as the “active surface” of the integrated circuit die.
The active surface 12 of the integrated circuit die 10 is electrically coupled to the package substrate 20 via solder bumps 30. In one embodiment, hundreds of solder bumps 30 may be used to provide electrical connectivity between the package substrate 20 and the integrated circuit die 10. In some cases the coefficient of expansion of the silicon integrated circuit die 10 may be many times lower than that of the package substrate 20. An underfill material 40 is used to fill the areas around the solder bumps between the integrated circuit die 10 and the package substrate 20 and helps to reduce the stresses caused by the difference in thermal expansion of the two materials.
A heat spreader 50 covers the integrated circuit die and forms an air-filled chamber 52. In some cases, a thermal material 54 is placed between the integrated circuit die and the heat spreader to help conduct heat away from the integrated circuit die 10.
Various types of leads 60 extend from the integrated circuit package 5. These leads are used to couple the integrated circuit package to a printed circuit board. The leads 60 may be any of various types such as solder bumps, ball grid array (BGA), pin grid array (PGA), surface mount, and so forth.